Changing the Oracle database default maintenance window time

I’ve been working recently on a system that has been a performance nightmare. I’ve been able to do a lot to get it running well, but I often noticed that load on the system would always increase in the afternoon even though it didn’t appear the workload was increasing. I’d notice this often around 3-4PM (Mountain Time) and thought maybe it was because people in the East and Central time zones were returning home and using it. I had observed however, that the traffic pattern would rise in the morning, stay high during the day, and then lower in the afternoon and into the evening. This made my theory not make sense. It didn’t make sense the load would increase when traffic on the system should be going down, until one day I did “date” on the Linux command line and got reminded the system runs on UTC and this system supports customers in North America. Ah-hah!

Some quick time math revealed that 3PM (Mountain Time) was 10PM UTC. What did that matter? Well, I recalled from OCP study that the default Oracle Database maintenance windows start at 10PM during the week. That meant that the Oracle maintenance windows would be starting during the normal user time for this product. I wanted to modify these to get them to start during the North American night.

My recollection was that Oracle had weeknight and weekend windows and that is what I’d need to change. I searched for these to verify the start time:

The next day I checked the scheduler to see if the jobs ran at the new correct time. I checked in dba_scheduler_job_details but couldn’t find what I wanted. Some research reminded me that in 11g the DBMS_AUTO_TASK_ADMIN functionality is used. To find the information I needed to check another view: